German authorities have revealed that unknown perpetrators attacked scores of art and antiquities at several museums in central Berlin earlier this month, on an annual holiday that commemorates Germany’s peaceful reunification.

The vandals poured an oily liquid on more than 70 works of art and antiquities at the Pergamon Museum, the Alte Nationalgalerie, the Neues Museum, and the Pergamonmuseum Panorama exhibition site during museum opening hours on October 3, according to Berlin police. While the motivation for the attacks has not been uncovered, some suspect the involvement of right-wing propagandists.

Damaged works include Egyptian sarcophagi, paintings, as well as stone and wood sculptures at the four museums, which are all located on Museum island in the center of the German capital. The Prussian Cultural Heritage foundation says that a “small” amount of liquid was sprayed on the objects by perpetrators who “acted very covertly and apparently exploited moments in which the supervisory staff.” The foundation, which oversees the museums, says that in many cases the damage could be readily reversed, but that stone and wood sculptures are still being restored. Some works are back on view.

In a statement sent to Artnet News, Culture Minister Monika Grütters condemned the incident, calling it an attack against “cultural heritage, against civil forms of debate, and thus against principles of democracy.” Her office has also asked for a report from the Berlin state museums to understand how the damages occurred in the first place.

The incident has come to light weeks after it occurred due to reporting by the German outlets Deustchlandfunk and Die Zeit, which wrote that it was the most “extensive attack” on art and antiquities in Germany since World War II.

Few details have been uncovered about the motivations of the vandals. In confirming details of the incident to Artnet News, the police added that the public was not informed about the incident while an investigation has been ongoing. The department has asked for witnesses to come forward and has declined to give any more details that might compromise the investigation.

Some commentators have speculated that far-right extremists could be connected to the vandalism. Reporter Julius Geiler, who focuses on far-right extremism, tweeted that the vegan cookbook author and far-right conspiracy theorist Attila Hildmann could have incited the attacks.

Geiler supported this theory by pointing to alleged screenshots of Hildmann’s social media posts, which have since been deleted. On August 23, Hildmann, who is also a vocal coronavirus denier, allegedly called for the destruction of the Pergamon Museum on social media, calling it a “satanist” site and the “source of all evil.” According to another screenshot that is circulating on social media, Hildmann also called the Altes Museum “satan’s altar,” apparently amalgamating the two distinct institutions. The Guardian has also reported that Hildmann shared a newspaper report on the attack last night, writing “Fact! It is the throne of Baal (Satan).”

Felix Huesmann, another German journalist covering far-right and conspiracy theories, has explained that the idea that the Pergamon is a satanic altar has circulated online for years but that in recent months the theory has resurfaced on the messaging app Telegram.

[1:30 CET: This story has been updated to include new information and comments from the Prussian Cultural Heritage Foundation.]